Drying-kiln.



w as r H E. H PERKINS. DRYING KILN.

APPLICATION FILED DEO.3,1904.

' be the efiiciency of the mode of treatment.

'- densesthe moisture in the air, (the condenraise its temperature to the desired i sin srans ATENT orsro.

ELMER E. PERKI S, or MELROSE, MASSACHUSETTS. I

a osvme mm.

Specifibation of Letters Patent.

.To all wlwnt (it m/(ty concern:

Be it known that I, ELMER E. PERKINS, a citizen of the United States, residing at Melrose, county of Middlesex, and State of Massachusetts, have invented an Im rovement in Drying-Kilns, of which the fol owing description, in connection with the-accompanying dra wmgs, isv a specification like characters on the drawings re resenting like parts.

This invention as for itsobject the production of a drying-kiln of very high efficiency and of extremely simple structure, particularly adapted fcr the rapid and thorough drying of material containing a largelpercentage of moisturesuch aslumber, 'des, leather, &c.in a most economical manner. The subjection of such material to heated air extracts moisture therefrom at a rate de endent principally 'ul pon the dryness of t e incoming air and t e efiicienc with which the moisture-laden airis' with rawnnand fresh dry air supplied to take its place, and the less the amount of heat required the greater will In accordance with my present invention" the material to be dried is placed in a closed chamber and heated dry air is introduced to the lower part thereof, the air rising and taking up moisture from the material. Such moisture-laden Warm or hot air, as the case may be, passes from the upper part of the chamber to .condensing means, which cons'atebein removed by suitable means,) and the coole dry air descends and is conducted into the lower part of the chamber, being subjected to the action of heatin means to oint. This heated dry air being 1i ht, rises in the chamber, absorbs moisture from the material to be dried, and again passes over to the condenser, as before.

The whole cycle of operations is conducted in a closed housin the same air being alternately cooled an freed from m0isture and reheated in its dry state to absorb moisture from the material in the drying-chamber, sothat a continuous current of air is maintained therethrough.

It. will be obvious that by using the air over and over no heat is lost except that due to the action of the condenser, and b regulating the relative action of the con ensmg and heating means the operation is varied as to rapidity and in accordance with the particular requirements of the material being treated.

The bottonrof the chamber is provided with inlets increasing in area as they are farther fromthe main inlet for the cooled air,

- Patented Jan. so, 1906.

and curved "guides are provided adj acent'the said inlets to direct the air as it chamber. I

If desired, theYrapidit'y of the self-induced air-current-may be increased by mechanical means, as a fan, should the material to be dried call for such The various nove features of my invention willbe fully describedtin the subjoined specification and particularly pointed out in the following claims.

Figure 1 is a longitudinal sectional view on enters the greater rapidity of action.

the line 1 1, Fig. 2, of a drying-kiln embodg ing one, form of my invention, the uprig partition being broken out to show the condenser. Fig. 2 is a cross-section of the kiln on the line 2 2, Fig. 1, looking toward the right. Fig. 3 is an enlarged detail showing how the efiective surface of the condenser may be varied. Fig. 4 is a'plan view of convenient means for varying the action of the heating means. Fig-5 is a partial sectional detailsimilar to Fig. 2, showing mechanical means for increasing the rapidity of the aircurrent; and Fig. 6 IS a similar view showing a difierent arrangement of the heating means and the inlet to the drying-chamber.

. Referrin to Figs. 1 and 2, the kiln consistsof a c osed housing A, which may be a room or a building of any desired size and provided with one or more doors, as A Fi 2, divided by an upright partition A, exten ing from end to end into a large drying-chamber D and an adjacentsmaller compartment C, but of relatively large cross-sectional area, the top of the partition stopping short of the pre. erably curved roof- A of the housin to present an outlet a extending the lengt l of the drying-chamber.

The housing is made with a double bottom or floor a a, (see Fig. 2,) forming thereby a distribution or return com artment C, which communicates with the owerl plortion of the compartment C.

The compartments C C constitute species of flue or conduit, communicatirififit its upper end with the chamber D at a and at its lower end with the lower portion of the (see Fig. 2,) in the bottom a.

ings I said chamber by inlet-openings a a, &c.,

prevent the formation of eddies or short-circuiting of the air-currents passing throu h the chamber. The connecting portion of t e compartments 0 and C are curved, as shown at c in Fig. 2, to prevent the formation of dead-air spaces and to facilitate=the flow of the air current, and for a like reason the guides 6 V, &c., are curved, as shown.

' In the compartment C, I locate condensing means, shown as a double series of coils of pipin 'c, through which any suitable cooling or re igerating medium is circulated to reduce the temperature of the condenser to the desired point, the main inlet being shown at c and the outlet at 0 Figs. 1 and 3.

Any suitable arrangement. may be ado ted for. varying the effective condensing-sur ace, and herein I have shown the inlet ends of two adjacent coils connected by headers 1, communicating by pipes 2 with'the main inlet 0 (see Fig. 3) and provided with suitable valves 3, whilethe return-bends of each pair of coils communicate by headers 4 and pipes 5 with the main outlet.

The valves are located outside the housing,

and by-shutting off one or more sets of the coils the condensing-surface is decreased as may be necessary, it being obvious that more condensing-surface is required when there is much moisture in the air than when the latter is less fully charged.

The moistureladen heated air from the chamber D passes through the outlet a into the compartment 0 and contacts with the condensing means, the contained moisture being immediately condensed and dripping from the coils 0 into a suitable drip-trough, to be referred to, while the cooled dry air, being of greater specific gravity, descends in the compartment O and is directed thence by the compartment 0 to the inlets a a &c., and into the drying-chamber D at its lower portion.

I provide heating means adjacent the bottomof the chamber and in close proximity to the inlets to heat this dry air and raise its temperature to the requisite degree to act properly upon the material to be dried. To this end heating-coils h h are shown in Figs. 1 and 2, located within the drying-chamber and just above the inlets a a &c., so that the incoming dry air as it passes around the These opencoils is rapidly'h'eated thereby and rises in the chamber to take up additional moisture from the material therein. v

It will be Inanifest that the rising heated air acts as a suction to draw more air up into the chamber from the compartment 0, while the descending cool air in the condensingco mpartnient G acts to's'ilck in moist warm air at its upper end. current of air is maintained in circulation through the chamber, passing out of it at its upper portion and into it at the bottom, the same air bein used over and over, and alternately dried y the condenser and more or less im regnated with moisture by the mate-. rial to e dried.

The heating-coils h are preferably so constructed that the effective heating surface may be varied, so that the apparatus may 0 erate in the most economical manner, and t e arrangement may be such as shown in detail in Fig. 4.

The main inlet is shown at h, connected by pi es 6 with the inlet sides of the several coils and provided with controlling-valves 7, while the main return or exhaust is shown at h and connected with the return sides of the coils. By means of the valves 7 any of the coils of each group can be shut off or cut out, thereby reducing the heating-surface as desired. For instance, in dryin very green lumber at the beginning the full condenser action will be necessary, as the water in the lumber will be given up rapidly to the hot air at first, and the temperature'of the dry air will be relatively high. As the drying progresses, however, the moisture in the lumber will be given off more slowly, so that some of the condenser can be cut out and also some of the heating-coils.

Drip-troughs 8 are shown as substantially U-shaped in cross-section, located beneath each vertical set of the condenser-coils c and close thereto to interfere as little as possible with the free circulation of the air-current,

Thus a continuous the drip-troughs being inclined longitudinally to enable the condensate to flow readily to the lower end.

A discharge-pipe 9, connected with the troughs, passes through the wall of the housing A and may be provided with a valve 10, Fig. 1, so that the outflow will practically keep the pipe 9 full, preventing the escape of the air from the housing or the entrance thereto of outside air.

It will be seen that the width of the condensing-chamber is such as to aiiord ample passage for the air traversing the chamber to prevent any throttling or back pressure, either of which would result in holding back the moist air in the drying-chamber and cause it to become overheated and improperly act upon the material to be treated.

When the material to be dried is placed in the chamber and the openings thereto closed,

will be at once begunand maintained, the air being dried by condensation of its C0117 tained moisture as it is subjected to the action of the condenser, so that the air is dry when entering the lower portion ofthe drying-chamber.

Should it be desirable to increase the rapidity of the circulation, fans may be introduoed in the conduit or circulation-compartment, as at F, Fig. 5, wherein the fan is shown at the lower end of the compartment C, to draw the air down through it and force it into compartment 0 and thence to the chamber D.

In-practice the fans would be arranged along the length of the housing, as many as necessary, according to the capacity of the chamber and the rapidity of current desired.

The fans may be driven in any suitable m annerelectrically, by bolting, or otherwise.

In Fig. 6 I have shown the inlet-opening a, in the floor of the chamber D about midway between its front wall and the partition A, and the heating-coils h are grouped beneath the inlet in the compartment C.

Above the inlet, vanes or guides b are arranged to direct some of the incoming current of dry heated air toward the front and back of the drying-chamber to better distribute the current through the chamber.

Having fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

I 1. In a drying-kiln, a closed housing having an upright'partition dividing it into a drying-chamber and an adjacent compartment of relatively large cross sectional area communicating therewith at its upper end, a double bottom for the chamber, directly connected with the lower end of said compartment and having inlets into the chamber increasing in area as the are farther from the compartment, curve condenser in the compartment, and heating means adjacent the inlets into the chamber,

the alternate heating and cooling on opposite sides of the partition ca'usin a continuous and free air-current through t echamber, the

' variations in the areas of the inlets and the uniform guides adjacent the inlets 0d direct the air as it enters the chamber, a

venting the formation of eddies and deadspaces, 7

2. In a drying-kiln, a closed housing-having an uprightpartition dividing it into adrying-chamber and an adjacent compartment of relatively large cross-sectional area communicating therewith at its u per end, a double bottorn'for the chamber, irectly connected with the lower end of said compartment and having inlets into the chamber increasing in area as the are farther from the compartment, curve guides adjacent the inlets and extending both above and beloW the plane in which the inlets are located, to dlrect the air as it enters'the chamber, a condenser in the compartment, and heating means ad.- j acent the inlets into the chamber, the alternate heating and cooling on opposite sides of the partition causing a continuous and free air-current through the chamber, the varia-. tions in the areas of the inlets and the curved guides distributing the incoming air uniformly throughout the chamber, and preventing the formation of eddies and deadspaces.

3. In a drying-kiln, a closed housing having a transversely-curved roof and an upright partition dividing the housing into a drying-chamber and an adjacent condensingcompartment communicating therewith at its upper end, a double bottom for the chamber, having a direct and curved connection with the lower .end of said compartment and having inlets into the chamber increasing in area as they are farther away from the compartment, curved guides adjacent the inlets to direct the air as it enters the chamber, and heating means adjacent said inlets, the alternate heating and cooling on opposite sides of the partition" causing a continuous and free air-current through the chamber, the varla tions, in the areas of the inlets and the curved guides distributing-the incomin a ir uniforml throughout the chamber, an acting, wlt the curved roof and the curved connection between the compartment and :the double bottom of the chamber, to prevent the formation of eddies and (lead s aces.

In testimony whereo I have signed my name to this specification in the presence of two subscribing witnesses.

ELME'R ESISERKINS.

Witnesses JoHN Q. E1)wARns, MARGARET A. DUNN. 

